What is Leptin?
Leptin is a hormone and biomarker (S-Leptin) that is primarily produced by adipose tissue in the body. It plays a central role in the regulation of appetite, body weight and energy balance. Leptin sends signals to the hypothalamus in the brain and acts as a "satiety signal" to reduce hunger and stimulate energy expenditure. The production of leptin is proportional to the amount of body fat, which means that higher levels of body fat often lead to higher levels of leptin in the blood.
Leptin is transported via the blood and binds to leptin receptors in various tissues. The biological effect of leptin depends on the leptin concentration in combination with the availability of functional receptors and the body's sensitivity to the hormone. Leptin levels are often higher in women than in men even when taking into account the amount of body fat. This is thought to be due to hormonal differences, especially the influence of estrogen, which allows leptin to have specific roles in women's reproductive health.
Possible link to inflammatory processes
Leptin is not only a satiety signal but also plays a role in the body's immune system. The hormone affects inflammatory processes by stimulating the production of pro-inflammatory cytokines. Elevated leptin levels in obesity have been linked to chronic low-grade inflammation, which can increase the risk of metabolic diseases, cardiovascular diseases and certain autoimmune conditions.
Leptin and the sleep cycle
Leptin is also affected by sleep quality and quantity. Lack of sleep can lead to reduced leptin levels, which can cause increased hunger and negatively affect energy balance. This is an important aspect to highlight in connection with weight management and healthy lifestyle habits.
Why is S-Leptin analyzed?
Analysis of S-Leptin is carried out in order to provide more information about the body's energy balance and metabolism. Elevated leptin levels are often seen in obesity and may indicate leptin resistance, a condition in which the body does not respond to leptin's satiety signals despite high levels. This can lead to increased hunger and weight gain. Low leptin levels, on the other hand, can be related to underweight, starvation or other conditions in which adipose tissue production of leptin is impaired.
Leptin analysis is also used in research to understand the hormone's role in various metabolic and inflammatory diseases, such as diabetes, cardiovascular diseases and certain autoimmune conditions.
S-Leptin and body weight
Leptin is an important regulator of body weight, as it helps to balance energy intake with energy expenditure. In individuals of normal weight, leptin functions as a signaling system that counteracts overeating. In obesity, this system can often be out of balance, which can cause leptin resistance. This means that the brain does not respond adequately to leptin signals, which can lead to continued overeating and weight gain despite high leptin levels.
Common symptoms of leptin imbalance
Unbalanced levels of leptin can cause different symptoms depending on whether the hormone is elevated or lowered. Here are some common symptoms that can be related to leptin imbalance.
- Increased hunger and weight gain (in case of leptin resistance)
- Difficulty losing weight despite diet and exercise
- Reduced metabolism
- Reduced appetite and underweight (in case of low leptin levels)
- Fatigue and low energy levels
- Impact on fertility and hormonal balance
Diagnostic uses
In addition to providing insight into energy balance and metabolism, leptin analysis is sometimes used in the investigation of specific conditions such as:
Hypothalamic amenorrhea (when menstruation fails due to low energy availability).
Genetic defects that affect leptin production or leptin receptors, which can lead to extreme obesity at a young age.
Assessment of metabolism in severe diseases such as cancer cachexia (weight loss and muscle loss in cancer).
Treatment options for abnormalities
In some specific cases, such as genetic leptin deficiency, treatment with synthetic leptin can be an effective therapy. However, this is very rare and is only used in special medical situations.